Bank card linking means that the user adds a credit card as an associated card to his or her personal online banking account. After activating online banking, users can add all the bank cards in their name to online banking. After adding a bank card, users can easily check the balance and status of the bank card, and realize automatic repayment between bank cards and credit cards. Credit cards, also called credit cards, are mainly used for overdraft consumption. After a user applies for a credit card, the bank will give them a certain limit, and the user can make overdraft purchases within the limit. After overdrafting the credit card, the user needs to repay, which is a way of spending first and repaying later. Situation when changing the card without changing the number: The user needs to replace the card because the old card is damaged and needs to be replaced with a new one. He can apply for a new card with the original card number at the surrounding bank service outlets, and the new card can be approved within a week; the user needs to replace the card because the old card is damaged. When a new card needs to be replaced, the new card number will change in most cases, and users can obtain a new card immediately.